Mechanical resonator of rotation

ABSTRACT

A mechanical resonator of rotation, particularly for use in a timepiece, comprising an oscillatory mass having an axis of symmetry, a support, spring means connecting said mass to said support for oscillation of the latter about a rotational axis substantially coinciding with said axis of symmetry, said spring means including leaf springs consisting of rectilinear active sections interconnected by connecting elements adapted to be very rigid with respect to the effective stresses of oscillation and determining the useful length of said active sections; preferably, said springs are obtained by suitably folding single cut out pieces.

United States Patent [191 Favre [4 1 Jan. 1,1974

[75] Inventor: Robert Favre, Lausanne,

Switzerland [73] Assignee: Fabriques Morado, Canton of Neuchatel, Switzerland [22] Filed: Mar. 14, 1972 [21] Appl. No.: 234,571

Related US. Application Data [63] Continuation of Ser. No. 39,785, May 22, 1970,

FOREIGN PATENTS OR APPLICATIONS 1,108,028 3/1968 Great Britain 58/23 TF 1,067,148 5/1967 Great Britain 58/23 TF 1,510,547 12/1967 France 58/23 TF Primary Examiner-Charles J. Myhre Assistant Examiner-Wesley S. Ratliff, Jr. Attorney-Dwight H. Smiley [57] ABSTRACT A mechanical resonator of rotation, particularly for use in a timepiece, comprising an oscillatory mass having an axis of symmetry, a support, spring means connecting said mass to said support for oscillation of the latter about a rotational axis substantially coinciding with said axis of symmetry, said spring means including leaf springs consisting of rectilinear active sections interconnected by connecting elements adapted to be very rigid with respect to the effective stresses of oscillation and determining the useful length of said active sections; preferably, said springs are obtained by suitably folding single cut out pieces.

6 Claims, 6 Drawing Figures 1 MECHANICAL RESONATOR OF ROTATION This is a continuation, of application Ser. No. 39,785,

filed May 22, 1970 now abandoned.

The present invention relates to a mechanical resonator of rotation, particularly for use in a timepiece.

The resonator described in my prior US. Pat. No. 3,528,308 (application Ser. No. 737,002) comprises, in combination, an oscillatory mass having an axis of symmetry perpendicular to a predetermined plane, a support, spring means connecting said mass to said support for oscillation of the latter about a rotational axis substantially coinciding with said axis of symmetry, said spring means including at least one leaf spring having a width substantially greater than its thickness and arranged with its widthwise faces perpendicular to said predetermined plane, said leaf spring being secured at one end to said support and at its other end to said mass, said leaf spring including elongate arm portions extending generally radially with respect to said axis and in closely spaced opposition to each other in sideby-side relation in a direction normal to said axis whereby to resist both radial and axial displacement of said mass with respect to its rotational axis under shock loading conditions.

Practically, the active portion of the spring or springs consists of rectilinear or substantially rectilinear sections, interconnected by strongly curvilinear, hair-pinshaped sections. The curvilinerar active sections have a double drawback:

a. They are difficult, if not impossible to manufacture with a great mechanical precision;

b. They involve unavoidably a heterogeneity in the cold-working defavorably affecting the elastic characteristics of the spring.

It is possible to overcome these drawbacks by replacing the strongly curvilinear active sections by so-called connecting elements" presenting a strong rigidity with respect to the effective stresses of oscillation, in such a manner that these connecting elements practically do not participate in the useful elastic deformations of the system.

The present invention just relates to a resonator of the type referred to, described in the above-mentioned patent, this resonator being broadly characterized in that its elastic structure comprises springs consisting of rectilinear active sections interconnected by connecting elements adapted to be relatively very rigid with respect to the effective stresses of oscillation and determining in a precise manner the useful length of the active sections, in such a manner that only the active sections, of a well determined length, practically intervene in the process of elastic deformation of oscillation.

The accompanying drawings illustrate, by way of example, two embodiments of the invention. There has been represented in the drawings only what is necessary for an undeistanding of the invention.

FIG. 1 is a view of a plan cutting out of a spring according to the first embodiment, before folding.

FIG. 2 is a view of the folded spring, projected onto a plane parallel to the plane of oscillation.

FIG. 3 is a view of the folded spring, projected onto a plane perpendicular to the plane of oscillation.

FIGS. 4 to 6 are corresponding views of the spring ac-- cording to the second embodiment. I

FIG. 1 illustrates in' a plan view the three rectilinear sections 1, 2 and 3 which will constitute the only active parts of the folded spring. The intermediary connecting elements are shown as at 4 and 5, whereas the end connecting elements are shown as at 6 and 7. The tongue 8 is adapted for carrying a pawl serving for converting the reciprocating motion of oscillation into a unidirectional rotating movement through the intermediary of a conventional ratchet wheel (not shown).

I FIGS. 2 and 3 are two orthogonal views of the spring folded along the dotted lines of FIG. 1, all of the foldings being made at right angles, except that of the pawlholder 8, which has to be adapted to the operation geometry. The active sections 1, 2 and 3 are viewed parallel to one another in FIG. 2, which is a projection onto the plane of oscillation, whereas they are partially superposed in FIG. 3, which is perpendicular to the plane of oscillation.

The connecting elements 4 and 5 are rigidified with respect to the stresses of oscillation due to the orientation of the adjacent foldings, which are here inclined at 45 with respect to the plane of oscillation, this orientation being clearly seen in FIG. 3. This inclined arrangement enables the connecting elements 4 and 5 to oppose also a high resistance to the parasitic stresses perpendicular to the plane of oscillation, which would not be the case if the connecting elements were disposed so as to be situated in the plane of oscillation.

The end connecting elements 6 and 7 have to render possible the fixing of the spring by welding. To this end, these elements are folded so as to be situated in the plane of oscillation, this enabling .to make a tangential welding practically without any static constraint of the spring, this being an important condition for keeping its chronometric performances.

FIG. 4 illustrates in a plan view a spring according to the second embodiment, before folding. This spring includes the three rectilinear sections 9, l0 and 11 which will constitute the only active parts of the folded spring. The intermediary connecting elements are shown as at 12 and 13, whereas the end connecting elements are shown as at 14 and 15. The tongue 16 serves for fixing a pawl adapted to convert the oscillation motion into a unidirectional rotary motion through the intermediary of a conventional ratchet wheel.

FIGS. 5 and 6 are two orthogonal views of the spring folded along the dotted lines of FIG. 4, all of the foldings being made at right angles, except that of the pawlholder 16..The active sections 9, l0 and 11 are viewed parallel to one another in FIG. 5, which is a projection onto the plane of oscillation, whereas they are viewed partially superposed in FIG. 6, which is perpendicula to the plane of oscillation.

The connecting elements 12 and 13 are situated in the plane of oscillation, so that they oppose a maximum resistance to the useful stresses of oscillation.

The end connecting elements 14 and 15 have to permit the fixing of the spring by welding. To this end, these elements are folded so as to be situated in the plane of oscillation, thus rendering possible a tangential welding practically without any static constraint of the spring, which is an important condition for keeping its chronometric performances.

As described in the above-mentioned patent, the complete elastic structure of a resonator involves the use of eight elementary springs such as described above, namely fou-r springs for each oscillatory mass.

What I claim is:

1. An elastic structure for use'in a mechanical resonator of rotation between the angularly displaceable mass of said resonator and a stationary point radially inward of said mass comprising: a flat leaf spring having a width substantially exceeding its thickness and consisting of retilinear active sections interconnected by planar connecting sections extending the distance between said active sections and disposed in a plane substantially at a right angle with respect to the planes of said active sections, said connecting sections being relatively very rigid with respect to the effective stresses of oscillation and determining the functional length of the active sections, whereby only the active sections of said determined functional length substantially participate in the process of elastic deformation of oscillation, said active sections being oscillatable in a direction generally perpendicular to the planes thereof.

2. A structure according to claim 1, characterized in that each of the said springs is a unitary cut out piece.

3. A structure according to claim 2, characterized in that the intermediary connecting sections are inclined with respect to the plane of oscillation, so as to oppose a great resistance both to the useful stresses of oscillation and to the parasitic stresses perpendicular to the plane of oscillation.

4. A structure according to claim 3, characterized in that the intermediary connecting sections are inclined at 45 with respect to the plane of oscillation.

5. A structure according to claim 2, characterized in that the intermediary connecting sections are situated in the plane of oscillation, so as to oppose a maximum resistance to the useful stresses of oscillation.

6. A structure according to claim 2, characterized in that the connecting sections situated at each end of the spring lie in a plane parallel to the plane of oscillation, so as to render possible a flat welding, without any static constraint of the spring.

i fimTE STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,782,209 Dated n ry 1, 1974 Inverit0r(s) Robert Favre It is certified that error appears in the above-identified patent I and that said Letters Patent are hereby corrected as shown below:

Priority Data:

Switzerland "Aop'lication No. 8483 filed June 4, 1969 Signed and aealei this 11 h day of Jfine lQ'Zlp (SEAL) Attest:

EDWARD nmmcimmm. c. MARSHALLDANN 4 I Attesting Officer commissioner o1v Patents PC4050 ('|O-69) Q Q I uscom pc 5 7g.p

1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,782,209 Dated January 1, 1974 Inventor (5) Robert Favre It is certified that error appears in'the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Priority Data:

Switzerland Application No. 8483 filed June 4, 1969 Signed and Sealed this llth day of June 1971;. v

(SEAL) Attest: r

EDWARD H.F'LETCHER,JR. c. MARSHALL mm: Atteating Officer fionmissioner of Patents 

1. An elastic structure for use in a mechanical resonator of rotation between the angularly displaceable mass of said resonator and a stationary point radially inward of said mass comprising: a flat leaf spring having a width substantially exceeding its thickness and consisting of retilinear active sections interconnected by planar connecting sections extending the distance between said active sections and disposed in a plane substantially at a right angle with respect to the planes of said active sections, said connecting sections being relatively very rigid with respect to the effective stresses of oscillation and determining the functional length of the active sections, whereby only the active sections of said determined functional length substantially participate in the process of elastic deformation of oscillation, said active sections being oscillatable in a direction generally perpendicular to the planes thereof.
 2. A structure according to claim 1, characterized in that each of the said springs is a unitary cut out piece.
 3. A structure according to claim 2, characterized in that the intermediary connecting sections are inclined with respect to the plane of oscillation, so as to oppose a great resistance both to the useful stresses of oscillation and to the parasitic stresses perpendicular to the plane of oscillation.
 4. A structure according to claim 3, characterized in that the intermediary connecting sections are inclined at 45* with respect to the plane of oscillation.
 5. A structure according to claim 2, characterized in that the intermediary connecting sections are situated in the plane of oscillation, so as to oppose a maximum resistance to the useful stresses of oscillation.
 6. A structure according to claim 2, characterized in that the connecting sections situated at each end of the spring lie in a plane parallel to the plane of oscillation, so as to render possible a flat welding, without any static constraint of the spring. 